This work is focused on several aspects of the biogenesis of lysosomes. The isolation and biosynthesis of several of the multiple forms of Beta-glucuronidase are being investigated in rat liver and cultured cells. The biosynthetic and purification are being carried on with the use of an anti-rat preputial gland Beta-glucuronidase antibody which cross reacts with all forms of rat liver Beta-glucuronidase.